Question: A box contains $4$ red marbles, $4$ green marbles, and $4$ blue marbles. If a marble is randomly chosen, what is the probability that it is blue?
Answer: There are $4 + 4 + 4 = 12$ marbles in the box. There are $4$ blue marbles. The probability is $ \frac{4}{12} = \dfrac{1}{3}$.